Class: QgsMapToolIdentify¶

Map tool for identifying features in layers

after selecting a point, performs the identification:

for raster layers shows value of underlying pixel
for vector layers shows feature attributes within search radius (allows editing values when vector layer is in editing mode)

Class Hierarchy¶

Base classes¶

`QgsMapTool`	Abstract base class for all map tools. Map tools are user interactive tools for manipulating the map canvas. For example map pan and zoom features are implemented as map tools.
QObject

Subclasses¶

QgsMapToolIdentifyFeature

The QgsMapToolIdentifyFeature class is a map tool to identify a feature on a chosen layer. Once the map tool is enable, user can click on the map canvas to identify a feature. A signal will then be emitted.

Methods

`derivedAttributesForPoint`	Returns derived attributes map for a clicked point in map coordinates.
`formatChanged`
`identify`	Performs the identification.
`identifyLayer`	Call the right method depending on layer type
`identifyMenu`	Returns a pointer to the identify menu which will be used in layer selection mode this menu can also be customized
`identifyMeshLayer`	Identifies data from active scalar and vector dataset from the mesh layer
`identifyRasterLayer`	Performs the identification against a given raster layer.
`identifyVectorLayer`	Performs the identification against a given vector layer.
`restoreCanvasPropertiesOverrides`	Clears canvas properties overrides previously set with `setCanvasPropertiesOverrides()`
`setCanvasPropertiesOverrides`	Overrides some map canvas properties inside the map tool for the upcoming identify requests.

Signals

`changedRasterResults`	Emitted when the format of raster results is changed and need to be updated in user-facing displays.
`identifyMessage`	Emitted when the identify operation needs to show a user-facing message
`identifyProgress`	Emitted when the identify action progresses.

Attributes

`ActiveLayer`
`AllLayers`
`DefaultQgsSetting`
`LayerSelection`
`MeshLayer`
`PointCloudLayer`
`RasterLayer`
`TopDownAll`
`TopDownStopAtFirst`
`VectorLayer`
`VectorTileLayer`

class qgis.gui.QgsMapToolIdentify[source]¶

Bases: QgsMapTool

__init__(canvas: QgsMapCanvas | None)

constructor

Parameters:: canvas (Optional[QgsMapCanvas])

ActiveLayer = 0¶

AllLayers = 31¶

DefaultQgsSetting = -1¶

class IdentifyMode¶: Bases: int

class IdentifyResult¶

class IdentifyResult(layer: QgsMapLayer | None, feature: QgsFeature, derivedAttributes: Dict[str | None, str | None])

class IdentifyResult(layer: QgsMapLayer | None, label: str | None, fields: QgsFields, feature: QgsFeature, derivedAttributes: Dict[str | None, str | None])

class IdentifyResult(a0: QgsMapToolIdentify.IdentifyResult)

Bases: object

mAttributes¶

mDerivedAttributes¶

mFeature¶

mFields¶

mLabel¶

mLayer¶

mParams¶

LayerSelection = 3¶

class LayerType¶
class LayerType(f: QgsMapToolIdentify.LayerType | QgsMapToolIdentify.Type)
class LayerType(a0: QgsMapToolIdentify.LayerType): Bases: object

MeshLayer = 4¶

PointCloudLayer = 16¶

RasterLayer = 2¶

TopDownAll = 2¶

TopDownStopAtFirst = 1¶

class Type¶: Bases: int

VectorLayer = 1¶

VectorTileLayer = 8¶

signal changedRasterResults(results: List[QgsMapToolIdentify.IdentifyResult])[source]¶

Emitted when the format of raster results is changed and need to be updated in user-facing displays.

Parameters:: results (List[QgsMapToolIdentify.IdentifyResult])

derivedAttributesForPoint(self, point: QgsPoint) → Dict[str, str]¶

Returns derived attributes map for a clicked point in map coordinates. May be 2D or 3D point.

Parameters:: point (QgsPoint)
Return type:: Dict[str, str]

formatChanged(self, layer: QgsRasterLayer | None)[source]¶

Parameters:: layer (Optional[QgsRasterLayer])

identify(self, x: int, y: int, layerList: Iterable[QgsMapLayer] = [], mode: QgsMapToolIdentify.IdentifyMode = QgsMapToolIdentify.DefaultQgsSetting, identifyContext: QgsIdentifyContext = QgsIdentifyContext()) → List[QgsMapToolIdentify.IdentifyResult]¶

Performs the identification.

Parameters:

x (int) – x coordinates of mouseEvent
y (int) – y coordinates of mouseEvent
layerList (Iterable[QgsMapLayer] = []) – Performs the identification within the given list of layers. Default value is an empty list, i.e. uses all the layers.
mode (QgsMapToolIdentify.IdentifyMode = QgsMapToolIdentify.DefaultQgsSetting) – Identification mode. Can use QGIS default settings or a defined mode. Default mode is DefaultQgsSetting.
identifyContext (QgsIdentifyContext = QgsIdentifyContext()) – Identify context object.

Return type:

List[QgsMapToolIdentify.IdentifyResult]

Returns:

a list of IdentifyResult

identify(self, x: int, y: int, mode: QgsMapToolIdentify.IdentifyMode, layerType: QgsMapToolIdentify.LayerType | QgsMapToolIdentify.Type = QgsMapToolIdentify.AllLayers, identifyContext: QgsIdentifyContext = QgsIdentifyContext()) → List[QgsMapToolIdentify.IdentifyResult]

Performs the identification. To avoid being forced to specify IdentifyMode with a list of layers this has been made private and two publics methods are offered

Parameters:

x (int) – x coordinates of mouseEvent
y (int) – y coordinates of mouseEvent
mode (QgsMapToolIdentify.IdentifyMode) – Identification mode. Can use QGIS default settings or a defined mode.
layerType (Union[QgsMapToolIdentify.LayerType, QgsMapToolIdentify.Type] = QgsMapToolIdentify.AllLayers) – Only performs identification in a certain type of layers (raster, vector, mesh). Default value is AllLayers.
identifyContext (QgsIdentifyContext = QgsIdentifyContext()) – Identify context object.

Return type:

List[QgsMapToolIdentify.IdentifyResult]

Returns:

a list of IdentifyResult

identify(self, geometry: QgsGeometry, mode: QgsMapToolIdentify.IdentifyMode, layerType: QgsMapToolIdentify.LayerType | QgsMapToolIdentify.Type, identifyContext: QgsIdentifyContext = QgsIdentifyContext()) → List[QgsMapToolIdentify.IdentifyResult]

Performs identification based on a geometry (in map coordinates)

Parameters:

geometry (QgsGeometry)
mode (QgsMapToolIdentify.IdentifyMode)
layerType (Union[QgsMapToolIdentify.LayerType, QgsMapToolIdentify.Type])
identifyContext (QgsIdentifyContext = QgsIdentifyContext())

Return type:

List[QgsMapToolIdentify.IdentifyResult]

identify(self, geometry: QgsGeometry, mode: QgsMapToolIdentify.IdentifyMode, layerList: Iterable[QgsMapLayer], layerType: QgsMapToolIdentify.LayerType | QgsMapToolIdentify.Type, identifyContext: QgsIdentifyContext = QgsIdentifyContext()) → List[QgsMapToolIdentify.IdentifyResult]

Performs identification based on a geometry (in map coordinates)

Parameters:

geometry (QgsGeometry)
mode (QgsMapToolIdentify.IdentifyMode)
layerList (Iterable[QgsMapLayer])
layerType (Union[QgsMapToolIdentify.LayerType, QgsMapToolIdentify.Type])
identifyContext (QgsIdentifyContext = QgsIdentifyContext())

Return type:

List[QgsMapToolIdentify.IdentifyResult]

identify(self, x: int, y: int, mode: QgsMapToolIdentify.IdentifyMode, layerList: Iterable[QgsMapLayer], layerType: QgsMapToolIdentify.LayerType | QgsMapToolIdentify.Type = QgsMapToolIdentify.AllLayers, identifyContext: QgsIdentifyContext = QgsIdentifyContext()) → List[QgsMapToolIdentify.IdentifyResult]

Performs the identification. To avoid being forced to specify IdentifyMode with a list of layers this has been made private and two publics methods are offered

Parameters:

x (int) – x coordinates of mouseEvent
y (int) – y coordinates of mouseEvent
mode (QgsMapToolIdentify.IdentifyMode) – Identification mode. Can use QGIS default settings or a defined mode.
layerList (Iterable[QgsMapLayer]) – Performs the identification within the given list of layers.
layerType (Union[QgsMapToolIdentify.LayerType, QgsMapToolIdentify.Type] = QgsMapToolIdentify.AllLayers) – Only performs identification in a certain type of layers (raster, vector, mesh).
identifyContext (QgsIdentifyContext = QgsIdentifyContext()) – Identify context object.

Return type:

List[QgsMapToolIdentify.IdentifyResult]

Returns:

a list of IdentifyResult

identifyLayer(self, results: Iterable[QgsMapToolIdentify.IdentifyResult] | None, layer: QgsMapLayer | None, point: QgsPointXY, viewExtent: QgsRectangle, mapUnitsPerPixel: float, layerType: QgsMapToolIdentify.LayerType | QgsMapToolIdentify.Type = QgsMapToolIdentify.AllLayers, identifyContext: QgsIdentifyContext = QgsIdentifyContext()) → bool[source]¶

Call the right method depending on layer type

Parameters:

results (Optional[Iterable[QgsMapToolIdentify.IdentifyResult]])
layer (Optional[QgsMapLayer])
point (QgsPointXY)
viewExtent (QgsRectangle)
mapUnitsPerPixel (float)
layerType (Union[QgsMapToolIdentify.LayerType, QgsMapToolIdentify.Type] = QgsMapToolIdentify.AllLayers)
identifyContext (QgsIdentifyContext = QgsIdentifyContext())

Return type:

bool

identifyMenu(self) → QgsIdentifyMenu | None[source]¶

Returns a pointer to the identify menu which will be used in layer selection mode this menu can also be customized

Return type:: Optional[QgsIdentifyMenu]

identifyMeshLayer(self, results: Iterable[QgsMapToolIdentify.IdentifyResult] | None, layer: QgsMeshLayer | None, point: QgsPointXY, identifyContext: QgsIdentifyContext = QgsIdentifyContext()) → bool[source]¶

Identifies data from active scalar and vector dataset from the mesh layer

Works only if layer was already rendered (triangular mesh is created)

Added in version 3.6.

Parameters:

results (Optional[Iterable[QgsMapToolIdentify.IdentifyResult]])
layer (Optional[QgsMeshLayer])
point (QgsPointXY)
identifyContext (QgsIdentifyContext = QgsIdentifyContext())

Return type:

bool

signal identifyMessage(message: str)[source]¶

Emitted when the identify operation needs to show a user-facing message

Parameters:: message (str) – Message to show to the user

signal identifyProgress(processed: int, total: int)[source]¶

Emitted when the identify action progresses.

Parameters:

processed (int) – number of objects processed so far
total (int) – total number of objects to process

identifyRasterLayer(self, results: Iterable[QgsMapToolIdentify.IdentifyResult] | None, layer: QgsRasterLayer | None, point: QgsPointXY, viewExtent: QgsRectangle, mapUnitsPerPixel: float, identifyContext: QgsIdentifyContext = QgsIdentifyContext()) → bool[source]¶

Performs the identification against a given raster layer.

Parameters:

results (Optional[Iterable[QgsMapToolIdentify.IdentifyResult]]) – list of identify results
layer (Optional[QgsRasterLayer]) – raster layer to identify from
point (QgsPointXY) – point coordinate to identify
viewExtent (QgsRectangle) – view extent
mapUnitsPerPixel (float) – map units per pixel value
identifyContext (QgsIdentifyContext = QgsIdentifyContext()) – identify context object

Return type:

bool

identifyVectorLayer(self, results: Iterable[QgsMapToolIdentify.IdentifyResult] | None, layer: QgsVectorLayer | None, point: QgsPointXY, identifyContext: QgsIdentifyContext = QgsIdentifyContext()) → bool[source]¶

Performs the identification against a given vector layer.

Parameters:

results (Optional[Iterable[QgsMapToolIdentify.IdentifyResult]]) – list of identify results
layer (Optional[QgsVectorLayer]) – raster layer to identify from
point (QgsPointXY) – point coordinate to identify
identifyContext (QgsIdentifyContext = QgsIdentifyContext()) – identify context object

Return type:

bool

restoreCanvasPropertiesOverrides(self)[source]¶: Clears canvas properties overrides previously set with setCanvasPropertiesOverrides()

See also

setCanvasPropertiesOverrides()

Added in version 3.4.

setCanvasPropertiesOverrides(self, searchRadiusMapUnits: float)[source]¶

Overrides some map canvas properties inside the map tool for the upcoming identify requests.

This is useful when the identification is triggered by some other piece of GUI like a 3D map view and some properties like search radius need to be adjusted so that identification returns correct results. Currently only search radius may be overridden.

When the custom identification has finished, restoreCanvasPropertiesOverrides() should be called to erase any overrides.